Pionyr Immunotherapeutics’ Phase 1a Study of TREM1-targeting Antibody PY159 for the Treatment of Solid Tumors Featured at ASCO 2023

• PY159 was well tolerated with an acceptable safety profile over a range of doses both as a single agent and in combination with checkpoint inhibitor pembrolizumab
• Radiographic response included two partial responses and stable disease in nine subjects ranging in duration from 12 to more than 96 weeks
• A recommended dose for study expansion both as a single agent and in combination with pembrolizumab was derived, and enrollment of patients with metastatic refractory solid tumors into individual expansion cohorts of seven prespecified cancers is ongoing
• PY159 targets TREM1, a protein receptor highly expressed on the surface of immunosuppressive myeloid cells

Excerpt from the Press Release:

SOUTH SAN FRANCISCO, Calif.–(BUSINESS WIRE)–Pionyr Immunotherapeutics, Inc., a company developing first-in-class Myeloid Tuning™ antibody therapeutics that enhance the body’s antitumor immunity by altering, or “tuning,” immune cells within the tumor microenvironment, announced today that PY159, a monoclonal antibody targeting TREM1 (triggering receptor expressed on macrophages 1), was well-tolerated with signals of durable therapeutic activity in a Phase 1a dose-escalation study as a single agent and in combination with pembrolizumab. In 37 evaluable patients, two demonstrated partial responses and nine showed stable disease. A recommended dose of 3 mg/kg of PY159 has been determined, and seven expansion cohorts in prespecified indications are currently enrolling in the Phase 1b portion of the study. The study will be featured in a poster discussion session at the 2023 American Society of Clinical Oncology (ASCO) Annual Meeting, held June 2-6 in Chicago and virtually.

“PY159 is designed to activate the signaling of TREM1, which reprograms tumor-associated myeloid cells to stimulate anti-tumor immunity,” said Leonard Reyno, President, R&D and Chief Medical Officer of Pionyr Immunotherapeutics. “The radiographic response data provide encouraging signals of efficacy, which is exciting given the novel Myeloid Tuning approach we are pursuing. This response combined with acceptable safety and tolerability both as a monotherapy and in combination with checkpoint inhibitor demonstrate the potential of this approach for treating solid tumors.”

Safety and Tolerability as a Monotherapy and in Combination with Pembrolizumab Support Additional Clinical Studies

The Phase 1a dose-escalation study of PY159 was a non-randomized, open-label study to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of PY159 as a single agent and in combination with checkpoint inhibitor pembrolizumab in 37 subjects with advanced solid tumors

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